The document contains information about computer programming functions in three sections: 1. It defines a function and explains the basic components of a function like the function name, parameters, return type, and return statement. 2. It describes different ways a function can be called - by value, by reference, and passing an array by reference. It provides code examples to illustrate each case. 3. It discusses global and local variables, and variable modifiers like static and extern that change how variables can be accessed within and outside functions.

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type function-name(type arg-1,type arg-2,..., type arg-n)
{
variable-declaration;
statement-1;
statemetn-2;
...
statement-n;
return();
}
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#include stdio.h
#include conio.h
void About(void); Function Prototype
main(void)
{
About();
}
void About(void)
{
clrscr();
gotoxy(1,8);
printf(t***********************************n);
printf(t* Void Function, version 1.01 *n);
printf(t* MS-DOS, PC-DOS *n);
printf(t* *n);
printf(t* This product licensed to : *n);
printf(t* - *n);
printf(t* Gumtorn Ruanfaigad *n);
printf(t* - *n);
printf(t* ............................... *n);
printf(t* System resource : 75%% free *n);
printf(t***********************************n);
getch();
}
***********************************
* Void Function, version 1.01 *
* MS-DOS, PC-DOS *
* *
* This product licensed to : *
* - *
* Gumtorn Ruanfaigad *
* - *
* ............................... *
* System resource : 75% free *
***********************************

8. -4-
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#include stdio.h
void Add( int x, int y);
main(void)
{
int a = 1, b = 2;
clrscr();
Add(a,b);
Add(3,4);
getch();
}
void Add( int x, int y)
{
int result;
result = x + y;
printf( %d + %d = %dn, x, y, result);
return;
}
1 + 2 = 3
3 + 4 = 7

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#include stdio.h
void swap(int *ia , int *ib);
void main()
{
int a,b;
a = 123;
b = 456;
clrscr();
printf(a = %d , b = %dn,a,b);
swap(a,b);
printf(a = %d , b = %dn,a,b);
}
void swap(int *ia , int *ib)
{
int tmp;
tmp = *ia;
*ia = *ib;
*ib = tmp;
}
a = 123 , b = 45
a = 456 , b = 12

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11. #include stdio.h
void Add( int *x);
main(void)
{
int a[3] = {0,1,2};
clrscr();
Add(a);
Add(a);
Add(a);
getch();
}
void Add( int *x)
{
int result;
result = x[0] + x[1] + x[2];
printf( %d + %d + %d = %dn, x[0], x[1], x[2], result);
x[0] = result;
return;
}
0 + 1 + 2 = 3
3 + 1 + 2 = 6
6 + 1 + 2 = 9